The River Teifi (Welsh: Afon Teifi pronounced [ˈtəɪvɪ]) in Wales forms the boundary for most of its length between the counties of Ceredigion and Carmarthenshire, and for the final 3 miles (4.8 km) of its total length of 76 miles (122 km), the boundary between Ceredigion and Pembrokeshire. Its estuary is northwest of Cardigan, known in Welsh as Aberteifi, meaning 'mouth of the Teifi'. Teifi has formerly been anglicised as "Tivy".
